Circuit assemblies, lighting devices with such circuit assemblies as well as also methods for operating such circuit assemblies are extensively known in the prior art such that a separate printed evidence is not required hereto. Such circuit assemblies serve for supplying loads with electrical energy, which is provided by the electrical voltage source. In lighting devices, the load can be formed by an electrical circuit, which provides the lighting device with an additional function, which is not necessarily related to the actual lighting function of the lighting device. Hereby, so-called “smart” lighting devices can be provided, which allow additional functionality.
For the intended operation of the load, it is required to supply it with electrical energy, which is usually provided by the voltage source in lighting devices or the generic type, which also supplies the illuminant of the lighting device with electrical energy at the same time. For example, the voltage source can be a power supply unit, which is connected to a public energy supply network to be able to provide electrical energy from the public energy supply network for the intended operation of the lighting device. Usually, the voltage source is configured for the supply of the illuminant. Correspondingly, the voltage source comprises an internal resistance, which ensures the reliable and intended operation of the illuminant. With respect to the power and the internal resistance, the voltage source is thus usually adapted to the illuminant. If the load is now additionally supplied with electrical energy from the voltage source, thus, due to energy demand fluctuations of the load, voltage fluctuations at the voltage source can also occur due to the fluctuating load, which can affect the illuminant. For example, the brightness of the illuminant can be impaired by the voltage fluctuations such that corresponding brightness fluctuations can be the result. For example, if the illuminant comprises light emitting diodes or a light emitting diode array, the voltage source is usually formed for providing a preset current for the light emitting diodes or the light emitting diode array. The internal resistance of the voltage source can be correspondingly highly formed, in particular if it is desired to operate the light emitting diodes or the light emitting diode array with a substantially constant current. Here, energy demand fluctuations of the load can have a particularly unfavorable effect.
Of course, the above mentioned problem is not restricted to lighting devices, but can basically occur in an operation of voltage sources of general type. A voltage source with a high internal resistance, which exhibits distinct voltage fluctuations with different loadings, is also referred to as a soft energy source or soft voltage source. In the operation of the load at a soft energy source or voltage source, the voltage of the energy source or voltage source can drop if enough electrical energy for a linear current flow through a constant current circuit cannot be supplied to the load from the energy source or voltage source, for example if the load does not require a constant, but a pulsating current in a particular operating state, because it is cyclically switched on and off. Switching on and off result in corresponding current fluctuations, which result in corresponding voltage fluctuations at the energy source or voltage source due to the internal resistance.
Further, it is known in the prior art to reduce the above mentioned problem in that a bypass circuit is connected in parallel with the constant current circuit on the one hand and this parallel connection is connected to a voltage regulator circuit in the manner of a linear regulator, which couples the parallel connection to the voltage source. Therein, the bypass circuit is activated and deactivated, respectively, in time-controlled manner, namely depending on switching on the voltage source. The retroactive effect on the voltage source in switching on the voltage source can be reduced by this circuit, but the circuit proves to be very expensive and moreover requires a supplementary voltage range for the operation of a required upstream voltage regulator. The possibilities of employment of this circuit assembly are therefore limited.
Therefore, the invention is based on the object to specify a circuit assembly, a lighting device as well as a method, which allow improved supply of the electrical load with electrical energy from the voltage source.